// cuon-matrix.js (c) 2012 kanda and matsuda
/**
 * This is a class treating 4x4 matrix.
 * This class contains the function that is equivalent to OpenGL matrix stack.
 * The matrix after conversion is calculated by multiplying a conversion matrix from the right.
 * The matrix is replaced by the calculated result.
 */

/**
 * Constructor of Matrix4
 * If opt_src is specified, new matrix is initialized by opt_src.
 * Otherwise, new matrix is initialized by identity matrix.
 * @param opt_src source matrix(option)
 */
var Matrix4 = function (opt_src) {
    var i, s, d;
    if (opt_src && typeof opt_src === 'object' && opt_src.hasOwnProperty('elements')) {
        s = opt_src.elements;
        d = new Float32Array(16);
        for (i = 0; i < 16; ++i) {
            d[i] = s[i];
        }
        this.elements = d;
    } else {
        this.elements = new Float32Array([1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]);
    }
};

/**
 * Set the identity matrix.
 * 将Matrix4 实例 初始化单位阵
 * @return this
 */
Matrix4.prototype.setIdentity = function () {
    var e = this.elements;
    e[0] = 1;
    e[4] = 0;
    e[8] = 0;
    e[12] = 0;
    e[1] = 0;
    e[5] = 1;
    e[9] = 0;
    e[13] = 0;
    e[2] = 0;
    e[6] = 0;
    e[10] = 1;
    e[14] = 0;
    e[3] = 0;
    e[7] = 0;
    e[11] = 0;
    e[15] = 1;
    return this;
};

/**
 * Copy matrix.
 * @param src source matrix
 * @return this
 */
Matrix4.prototype.set = function (src) {
    var i, s, d;

    s = src.elements;
    d = this.elements;

    if (s === d) {
        return;
    }

    for (i = 0; i < 16; ++i) {
        d[i] = s[i];
    }

    return this;
};

/**
 * Multiply the matrix from the right.
 * @param other The multiply matrix
 * @return this
 */
Matrix4.prototype.concat = function (other) {
    var i, e, a, b, ai0, ai1, ai2, ai3;

    // Calculate e = a * b
    e = this.elements;
    a = this.elements;
    b = other.elements;

    // If e equals b, copy b to temporary matrix.
    if (e === b) {
        b = new Float32Array(16);
        for (i = 0; i < 16; ++i) {
            b[i] = e[i];
        }
    }

    for (i = 0; i < 4; i++) {
        ai0 = a[i];
        ai1 = a[i + 4];
        ai2 = a[i + 8];
        ai3 = a[i + 12];
        e[i] = ai0 * b[0] + ai1 * b[1] + ai2 * b[2] + ai3 * b[3];
        e[i + 4] = ai0 * b[4] + ai1 * b[5] + ai2 * b[6] + ai3 * b[7];
        e[i + 8] = ai0 * b[8] + ai1 * b[9] + ai2 * b[10] + ai3 * b[11];
        e[i + 12] = ai0 * b[12] + ai1 * b[13] + ai2 * b[14] + ai3 * b[15];
    }

    return this;
};
Matrix4.prototype.multiply = Matrix4.prototype.concat;

/**
 * Multiply the three-dimensional vector.
 * @param pos  The multiply vector
 * @return The result of multiplication(Float32Array)
 */
Matrix4.prototype.multiplyVector3 = function (pos) {
    var e = this.elements;
    var p = pos.elements;
    var v = new Vector3();
    var result = v.elements;

    result[0] = p[0] * e[0] + p[1] * e[4] + p[2] * e[8] + e[11];
    result[1] = p[0] * e[1] + p[1] * e[5] + p[2] * e[9] + e[12];
    result[2] = p[0] * e[2] + p[1] * e[6] + p[2] * e[10] + e[13];

    return v;
};

/**
 * Multiply the four-dimensional vector.
 * @param pos  The multiply vector
 * @return The result of multiplication(Float32Array)
 */
Matrix4.prototype.multiplyVector4 = function (pos) {
    var e = this.elements;
    var p = pos.elements;
    var v = new Vector4();
    var result = v.elements;

    result[0] = p[0] * e[0] + p[1] * e[4] + p[2] * e[8] + p[3] * e[12];
    result[1] = p[0] * e[1] + p[1] * e[5] + p[2] * e[9] + p[3] * e[13];
    result[2] = p[0] * e[2] + p[1] * e[6] + p[2] * e[10] + p[3] * e[14];
    result[3] = p[0] * e[3] + p[1] * e[7] + p[2] * e[11] + p[3] * e[15];

    return v;
};

/**
 * Transpose the matrix.
 * @return this
 */
Matrix4.prototype.transpose = function () {
    var e, t;

    e = this.elements;

    t = e[1];
    e[1] = e[4];
    e[4] = t;
    t = e[2];
    e[2] = e[8];
    e[8] = t;
    t = e[3];
    e[3] = e[12];
    e[12] = t;
    t = e[6];
    e[6] = e[9];
    e[9] = t;
    t = e[7];
    e[7] = e[13];
    e[13] = t;
    t = e[11];
    e[11] = e[14];
    e[14] = t;

    return this;
};

/**
 * Calculate the inverse matrix of specified matrix, and set to this.
 * @param other The source matrix
 * @return this
 */
Matrix4.prototype.setInverseOf = function (other) {
    var i, s, d, inv, det;

    s = other.elements;
    d = this.elements;
    inv = new Float32Array(16);

    inv[0] = s[5] * s[10] * s[15] - s[5] * s[11] * s[14] - s[9] * s[6] * s[15]
        + s[9] * s[7] * s[14] + s[13] * s[6] * s[11] - s[13] * s[7] * s[10];
    inv[4] = -s[4] * s[10] * s[15] + s[4] * s[11] * s[14] + s[8] * s[6] * s[15]
        - s[8] * s[7] * s[14] - s[12] * s[6] * s[11] + s[12] * s[7] * s[10];
    inv[8] = s[4] * s[9] * s[15] - s[4] * s[11] * s[13] - s[8] * s[5] * s[15]
        + s[8] * s[7] * s[13] + s[12] * s[5] * s[11] - s[12] * s[7] * s[9];
    inv[12] = -s[4] * s[9] * s[14] + s[4] * s[10] * s[13] + s[8] * s[5] * s[14]
        - s[8] * s[6] * s[13] - s[12] * s[5] * s[10] + s[12] * s[6] * s[9];

    inv[1] = -s[1] * s[10] * s[15] + s[1] * s[11] * s[14] + s[9] * s[2] * s[15]
        - s[9] * s[3] * s[14] - s[13] * s[2] * s[11] + s[13] * s[3] * s[10];
    inv[5] = s[0] * s[10] * s[15] - s[0] * s[11] * s[14] - s[8] * s[2] * s[15]
        + s[8] * s[3] * s[14] + s[12] * s[2] * s[11] - s[12] * s[3] * s[10];
    inv[9] = -s[0] * s[9] * s[15] + s[0] * s[11] * s[13] + s[8] * s[1] * s[15]
        - s[8] * s[3] * s[13] - s[12] * s[1] * s[11] + s[12] * s[3] * s[9];
    inv[13] = s[0] * s[9] * s[14] - s[0] * s[10] * s[13] - s[8] * s[1] * s[14]
        + s[8] * s[2] * s[13] + s[12] * s[1] * s[10] - s[12] * s[2] * s[9];

    inv[2] = s[1] * s[6] * s[15] - s[1] * s[7] * s[14] - s[5] * s[2] * s[15]
        + s[5] * s[3] * s[14] + s[13] * s[2] * s[7] - s[13] * s[3] * s[6];
    inv[6] = -s[0] * s[6] * s[15] + s[0] * s[7] * s[14] + s[4] * s[2] * s[15]
        - s[4] * s[3] * s[14] - s[12] * s[2] * s[7] + s[12] * s[3] * s[6];
    inv[10] = s[0] * s[5] * s[15] - s[0] * s[7] * s[13] - s[4] * s[1] * s[15]
        + s[4] * s[3] * s[13] + s[12] * s[1] * s[7] - s[12] * s[3] * s[5];
    inv[14] = -s[0] * s[5] * s[14] + s[0] * s[6] * s[13] + s[4] * s[1] * s[14]
        - s[4] * s[2] * s[13] - s[12] * s[1] * s[6] + s[12] * s[2] * s[5];

    inv[3] = -s[1] * s[6] * s[11] + s[1] * s[7] * s[10] + s[5] * s[2] * s[11]
        - s[5] * s[3] * s[10] - s[9] * s[2] * s[7] + s[9] * s[3] * s[6];
    inv[7] = s[0] * s[6] * s[11] - s[0] * s[7] * s[10] - s[4] * s[2] * s[11]
        + s[4] * s[3] * s[10] + s[8] * s[2] * s[7] - s[8] * s[3] * s[6];
    inv[11] = -s[0] * s[5] * s[11] + s[0] * s[7] * s[9] + s[4] * s[1] * s[11]
        - s[4] * s[3] * s[9] - s[8] * s[1] * s[7] + s[8] * s[3] * s[5];
    inv[15] = s[0] * s[5] * s[10] - s[0] * s[6] * s[9] - s[4] * s[1] * s[10]
        + s[4] * s[2] * s[9] + s[8] * s[1] * s[6] - s[8] * s[2] * s[5];

    det = s[0] * inv[0] + s[1] * inv[4] + s[2] * inv[8] + s[3] * inv[12];
    if (det === 0) {
        return this;
    }

    det = 1 / det;
    for (i = 0; i < 16; i++) {
        d[i] = inv[i] * det;
    }

    return this;
};

/**
 * Calculate the inverse matrix of this, and set to this.
 * @return this
 */
Matrix4.prototype.invert = function () {
    return this.setInverseOf(this);
};

/**
 * Set the orthographic projection matrix.
 * @param left The coordinate of the left of clipping plane.
 * @param right The coordinate of the right of clipping plane.
 * @param bottom The coordinate of the bottom of clipping plane.
 * @param top The coordinate of the top top clipping plane.
 * @param near The distances to the nearer depth clipping plane. This value is minus if the plane is to be behind the viewer.
 * @param far The distances to the farther depth clipping plane. This value is minus if the plane is to be behind the viewer.
 * @return this
 */
Matrix4.prototype.setOrtho = function (left, right, bottom, top, near, far) {
    var e, rw, rh, rd;

    if (left === right || bottom === top || near === far) {
        throw 'null frustum';
    }

    rw = 1 / (right - left);
    rh = 1 / (top - bottom);
    rd = 1 / (far - near);

    e = this.elements;

    e[0] = 2 * rw;
    e[1] = 0;
    e[2] = 0;
    e[3] = 0;

    e[4] = 0;
    e[5] = 2 * rh;
    e[6] = 0;
    e[7] = 0;

    e[8] = 0;
    e[9] = 0;
    e[10] = -2 * rd;
    e[11] = 0;

    e[12] = -(right + left) * rw;
    e[13] = -(top + bottom) * rh;
    e[14] = -(far + near) * rd;
    e[15] = 1;

    return this;
};

/**
 * Multiply the orthographic projection matrix from the right.
 * @param left The coordinate of the left of clipping plane.
 * @param right The coordinate of the right of clipping plane.
 * @param bottom The coordinate of the bottom of clipping plane.
 * @param top The coordinate of the top top clipping plane.
 * @param near The distances to the nearer depth clipping plane. This value is minus if the plane is to be behind the viewer.
 * @param far The distances to the farther depth clipping plane. This value is minus if the plane is to be behind the viewer.
 * @return this
 */
Matrix4.prototype.ortho = function (left, right, bottom, top, near, far) {
    return this.concat(new Matrix4().setOrtho(left, right, bottom, top, near, far));
};

/**
 * Set the perspective projection matrix.
 * @param left The coordinate of the left of clipping plane.
 * @param right The coordinate of the right of clipping plane.
 * @param bottom The coordinate of the bottom of clipping plane.
 * @param top The coordinate of the top top clipping plane.
 * @param near The distances to the nearer depth clipping plane. This value must be plus value.
 * @param far The distances to the farther depth clipping plane. This value must be plus value.
 * @return this
 */
Matrix4.prototype.setFrustum = function (left, right, bottom, top, near, far) {
    var e, rw, rh, rd;

    if (left === right || top === bottom || near === far) {
        throw 'null frustum';
    }
    if (near <= 0) {
        throw 'near <= 0';
    }
    if (far <= 0) {
        throw 'far <= 0';
    }

    rw = 1 / (right - left);
    rh = 1 / (top - bottom);
    rd = 1 / (far - near);

    e = this.elements;

    e[0] = 2 * near * rw;
    e[1] = 0;
    e[2] = 0;
    e[3] = 0;

    e[4] = 0;
    e[5] = 2 * near * rh;
    e[6] = 0;
    e[7] = 0;

    e[8] = (right + left) * rw;
    e[9] = (top + bottom) * rh;
    e[10] = -(far + near) * rd;
    e[11] = -1;

    e[12] = 0;
    e[13] = 0;
    e[14] = -2 * near * far * rd;
    e[15] = 0;

    return this;
};

/**
 * Multiply the perspective projection matrix from the right.
 * @param left The coordinate of the left of clipping plane.
 * @param right The coordinate of the right of clipping plane.
 * @param bottom The coordinate of the bottom of clipping plane.
 * @param top The coordinate of the top top clipping plane.
 * @param near The distances to the nearer depth clipping plane. This value must be plus value.
 * @param far The distances to the farther depth clipping plane. This value must be plus value.
 * @return this
 */
Matrix4.prototype.frustum = function (left, right, bottom, top, near, far) {
    return this.concat(new Matrix4().setFrustum(left, right, bottom, top, near, far));
};

/**
 * Set the perspective projection matrix by fovy and aspect.
 * @param fovy The angle between the upper and lower sides of the frustum.
 * @param aspect The aspect ratio of the frustum. (width/height)
 * @param near The distances to the nearer depth clipping plane. This value must be plus value.
 * @param far The distances to the farther depth clipping plane. This value must be plus value.
 * @return this
 */
Matrix4.prototype.setPerspective = function (fovy, aspect, near, far) {
    var e, rd, s, ct;

    if (near === far || aspect === 0) {
        throw 'null frustum';
    }
    if (near <= 0) {
        throw 'near <= 0';
    }
    if (far <= 0) {
        throw 'far <= 0';
    }

    fovy = Math.PI * fovy / 180 / 2;
    s = Math.sin(fovy);
    if (s === 0) {
        throw 'null frustum';
    }

    rd = 1 / (far - near);
    ct = Math.cos(fovy) / s;

    e = this.elements;

    e[0] = ct / aspect;
    e[1] = 0;
    e[2] = 0;
    e[3] = 0;

    e[4] = 0;
    e[5] = ct;
    e[6] = 0;
    e[7] = 0;

    e[8] = 0;
    e[9] = 0;
    e[10] = -(far + near) * rd;
    e[11] = -1;

    e[12] = 0;
    e[13] = 0;
    e[14] = -2 * near * far * rd;
    e[15] = 0;

    return this;
};

/**
 * Multiply the perspective projection matrix from the right.
 * @param fovy The angle between the upper and lower sides of the frustum.
 * @param aspect The aspect ratio of the frustum. (width/height)
 * @param near The distances to the nearer depth clipping plane. This value must be plus value.
 * @param far The distances to the farther depth clipping plane. This value must be plus value.
 * @return this
 */
Matrix4.prototype.perspective = function (fovy, aspect, near, far) {
    return this.concat(new Matrix4().setPerspective(fovy, aspect, near, far));
};

/**
 * Set the matrix for scaling.
 * @param x The scale factor along the X axis
 * @param y The scale factor along the Y axis
 * @param z The scale factor along the Z axis
 * @return this
 */
Matrix4.prototype.setScale = function (x, y, z) {
    var e = this.elements;
    e[0] = x;
    e[4] = 0;
    e[8] = 0;
    e[12] = 0;
    e[1] = 0;
    e[5] = y;
    e[9] = 0;
    e[13] = 0;
    e[2] = 0;
    e[6] = 0;
    e[10] = z;
    e[14] = 0;
    e[3] = 0;
    e[7] = 0;
    e[11] = 0;
    e[15] = 1;
    return this;
};

/**
 * Multiply the matrix for scaling from the right.
 * @param x The scale factor along the X axis
 * @param y The scale factor along the Y axis
 * @param z The scale factor along the Z axis
 * @return this
 */
Matrix4.prototype.scale = function (x, y, z) {
    var e = this.elements;
    e[0] *= x;
    e[4] *= y;
    e[8] *= z;
    e[1] *= x;
    e[5] *= y;
    e[9] *= z;
    e[2] *= x;
    e[6] *= y;
    e[10] *= z;
    e[3] *= x;
    e[7] *= y;
    e[11] *= z;
    return this;
};

/**
 * Set the matrix for translation.
 * 平移变换矩阵（x, y, z）
 * @param x The X value of a translation.
 * @param y The Y value of a translation.
 * @param z The Z value of a translation.
 * @return this
 */
Matrix4.prototype.setTranslate = function (x, y, z) {
    var e = this.elements;
    e[0] = 1;
    e[4] = 0;
    e[8] = 0;
    e[12] = x;
    e[1] = 0;
    e[5] = 1;
    e[9] = 0;
    e[13] = y;
    e[2] = 0;
    e[6] = 0;
    e[10] = 1;
    e[14] = z;
    e[3] = 0;
    e[7] = 0;
    e[11] = 0;
    e[15] = 1;
    return this;
};

/**
 * Multiply the matrix for translation from the right.
 * 从右边乘以平移矩阵
 * @param x The X value of a translation.
 * @param y The Y value of a translation.
 * @param z The Z value of a translation.
 * @return this
 */
Matrix4.prototype.translate = function (x, y, z) {
    var e = this.elements;
    e[12] += e[0] * x + e[4] * y + e[8] * z;
    e[13] += e[1] * x + e[5] * y + e[9] * z;
    e[14] += e[2] * x + e[6] * y + e[10] * z;
    e[15] += e[3] * x + e[7] * y + e[11] * z;
    return this;
};

/**
 * Set the matrix for rotation.
 * The vector of rotation axis may not be normalized.
 * @param angle The angle of rotation (degrees)
 * @param x The X coordinate of vector of rotation axis.
 * @param y The Y coordinate of vector of rotation axis.
 * @param z The Z coordinate of vector of rotation axis.
 * @return this
 */
Matrix4.prototype.setRotate = function (angle, x, y, z) {
    var e, s, c, len, rlen, nc, xy, yz, zx, xs, ys, zs;

    angle = Math.PI * angle / 180;
    e = this.elements;

    s = Math.sin(angle);
    c = Math.cos(angle);

    if (0 !== x && 0 === y && 0 === z) {
        // Rotation around X axis
        if (x < 0) {
            s = -s;
        }
        e[0] = 1;
        e[4] = 0;
        e[8] = 0;
        e[12] = 0;
        e[1] = 0;
        e[5] = c;
        e[9] = -s;
        e[13] = 0;
        e[2] = 0;
        e[6] = s;
        e[10] = c;
        e[14] = 0;
        e[3] = 0;
        e[7] = 0;
        e[11] = 0;
        e[15] = 1;
    } else if (0 === x && 0 !== y && 0 === z) {
        // Rotation around Y axis
        if (y < 0) {
            s = -s;
        }
        e[0] = c;
        e[4] = 0;
        e[8] = s;
        e[12] = 0;
        e[1] = 0;
        e[5] = 1;
        e[9] = 0;
        e[13] = 0;
        e[2] = -s;
        e[6] = 0;
        e[10] = c;
        e[14] = 0;
        e[3] = 0;
        e[7] = 0;
        e[11] = 0;
        e[15] = 1;
    } else if (0 === x && 0 === y && 0 !== z) {
        // Rotation around Z axis
        if (z < 0) {
            s = -s;
        }
        e[0] = c;
        e[4] = -s;
        e[8] = 0;
        e[12] = 0;
        e[1] = s;
        e[5] = c;
        e[9] = 0;
        e[13] = 0;
        e[2] = 0;
        e[6] = 0;
        e[10] = 1;
        e[14] = 0;
        e[3] = 0;
        e[7] = 0;
        e[11] = 0;
        e[15] = 1;
    } else {
        // Rotation around another axis
        len = Math.sqrt(x * x + y * y + z * z);
        if (len !== 1) {
            rlen = 1 / len;
            x *= rlen;
            y *= rlen;
            z *= rlen;
        }
        nc = 1 - c;
        xy = x * y;
        yz = y * z;
        zx = z * x;
        xs = x * s;
        ys = y * s;
        zs = z * s;

        e[0] = x * x * nc + c;
        e[1] = xy * nc + zs;
        e[2] = zx * nc - ys;
        e[3] = 0;

        e[4] = xy * nc - zs;
        e[5] = y * y * nc + c;
        e[6] = yz * nc + xs;
        e[7] = 0;

        e[8] = zx * nc + ys;
        e[9] = yz * nc - xs;
        e[10] = z * z * nc + c;
        e[11] = 0;

        e[12] = 0;
        e[13] = 0;
        e[14] = 0;
        e[15] = 1;
    }

    return this;
};

/**
 * 从右边乘上旋转矩阵.
 * 旋转轴的坐标不能被归一化.
 * @param angle 旋转角的角度（角度制非弧度制）
 * @param x 旋转轴向量 x坐标.
 * @param y 旋转轴向量 y坐标.
 * @param z 旋转轴向量 z坐标.
 * @return this
 */
Matrix4.prototype.rotate = function (angle, x, y, z) {
    return this.concat(new Matrix4().setRotate(angle, x, y, z));
};

/**
 * Set the viewing matrix.
 * @param eyeX, eyeY, eyeZ The position of the eye point.
 * @param centerX, centerY, centerZ The position of the reference point.
 * @param upX, upY, upZ The direction of the up vector.
 * @return this
 */
Matrix4.prototype.setLookAt = function (eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ) {
    var e, fx, fy, fz, rlf, sx, sy, sz, rls, ux, uy, uz;

    fx = centerX - eyeX;
    fy = centerY - eyeY;
    fz = centerZ - eyeZ;

    // Normalize f.
    rlf = 1 / Math.sqrt(fx * fx + fy * fy + fz * fz);
    fx *= rlf;
    fy *= rlf;
    fz *= rlf;

    // Calculate cross product of f and up.
    sx = fy * upZ - fz * upY;
    sy = fz * upX - fx * upZ;
    sz = fx * upY - fy * upX;

    // Normalize s.
    rls = 1 / Math.sqrt(sx * sx + sy * sy + sz * sz);
    sx *= rls;
    sy *= rls;
    sz *= rls;

    // Calculate cross product of s and f.
    ux = sy * fz - sz * fy;
    uy = sz * fx - sx * fz;
    uz = sx * fy - sy * fx;

    // Set to this.
    e = this.elements;
    e[0] = sx;
    e[1] = ux;
    e[2] = -fx;
    e[3] = 0;

    e[4] = sy;
    e[5] = uy;
    e[6] = -fy;
    e[7] = 0;

    e[8] = sz;
    e[9] = uz;
    e[10] = -fz;
    e[11] = 0;

    e[12] = 0;
    e[13] = 0;
    e[14] = 0;
    e[15] = 1;

    // Translate.
    return this.translate(-eyeX, -eyeY, -eyeZ);
};

/**
 * Multiply the viewing matrix from the right.
 * @param eyeX, eyeY, eyeZ The position of the eye point.
 * @param centerX, centerY, centerZ The position of the reference point.
 * @param upX, upY, upZ The direction of the up vector.
 * @return this
 */
Matrix4.prototype.lookAt = function (eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ) {
    return this.concat(new Matrix4().setLookAt(eyeX, eyeY, eyeZ, centerX, centerY, centerZ, upX, upY, upZ));
};

/**
 * Multiply the matrix for project vertex to plane from the right.
 * @param plane The array[A, B, C, D] of the equation of plane "Ax + By + Cz + D = 0".
 * @param light The array which stored coordinates of the light. if light[3]=0, treated as parallel light.
 * @return this
 */
Matrix4.prototype.dropShadow = function (plane, light) {
    var mat = new Matrix4();
    var e = mat.elements;

    var dot = plane[0] * light[0] + plane[1] * light[1] + plane[2] * light[2] + plane[3] * light[3];

    e[0] = dot - light[0] * plane[0];
    e[1] = -light[1] * plane[0];
    e[2] = -light[2] * plane[0];
    e[3] = -light[3] * plane[0];

    e[4] = -light[0] * plane[1];
    e[5] = dot - light[1] * plane[1];
    e[6] = -light[2] * plane[1];
    e[7] = -light[3] * plane[1];

    e[8] = -light[0] * plane[2];
    e[9] = -light[1] * plane[2];
    e[10] = dot - light[2] * plane[2];
    e[11] = -light[3] * plane[2];

    e[12] = -light[0] * plane[3];
    e[13] = -light[1] * plane[3];
    e[14] = -light[2] * plane[3];
    e[15] = dot - light[3] * plane[3];

    return this.concat(mat);
};

/**
 * Multiply the matrix for project vertex to plane from the right.(Projected by parallel light.)
 * @param normX, normY, normZ The normal vector of the plane.(Not necessary to be normalized.)
 * @param planeX, planeY, planeZ The coordinate of arbitrary points on a plane.
 * @param lightX, lightY, lightZ The vector of the direction of light.(Not necessary to be normalized.)
 * @return this
 */
Matrix4.prototype.dropShadowDirectionally = function (normX, normY, normZ, planeX, planeY, planeZ, lightX, lightY, lightZ) {
    var a = planeX * normX + planeY * normY + planeZ * normZ;
    return this.dropShadow([normX, normY, normZ, -a], [lightX, lightY, lightZ, 0]);
};

/**
 * Constructor of Vector3
 * If opt_src is specified, new vector is initialized by opt_src.
 * @param opt_src source vector(option)
 */
var Vector3 = function (opt_src) {
    var v = new Float32Array(3);
    if (opt_src && typeof opt_src === 'object') {
        v[0] = opt_src[0];
        v[1] = opt_src[1];
        v[2] = opt_src[2];
    }
    this.elements = v;
};

/**
 * Normalize.
 * @return this
 */
Vector3.prototype.normalize = function () {
    var v = this.elements;
    var c = v[0], d = v[1], e = v[2], g = Math.sqrt(c * c + d * d + e * e);
    if (g) {
        if (g == 1)
            return this;
    } else {
        v[0] = 0;
        v[1] = 0;
        v[2] = 0;
        return this;
    }
    g = 1 / g;
    v[0] = c * g;
    v[1] = d * g;
    v[2] = e * g;
    return this;
};

/**
 * Constructor of Vector4
 * If opt_src is specified, new vector is initialized by opt_src.
 * @param opt_src source vector(option)
 */
var Vector4 = function (opt_src) {
    var v = new Float32Array(4);
    if (opt_src && typeof opt_src === 'object') {
        v[0] = opt_src[0];
        v[1] = opt_src[1];
        v[2] = opt_src[2];
        v[3] = opt_src[3];
    }
    this.elements = v;
};
